1. Field of the Invention
The present invention relates to a thermally transferable image protective sheet that can provide a protective layer which can protect an image in a record produced by a nonsilver photographic color hard copy recording method such as an electrophotographic recording method, an ink jet recording method, or a thermal transfer recording method, can improve lightfastness and other properties to the record, and can realize a record having texture comparable to silver salt photographs by virtue of a good glossy impression of the image surface. The present invention also relates to a method for protective layer formation using the thermally transferable image protective sheet and a record produced by the method.
2. Prior Art
By virtue of the advance of digital cameras and color hard copy technology in recent years, prints having full-color images formed thereon by a nonsilver photographic method, such as an electrophotographic recording method, an ink jet recording method, or a thermal transfer recording method, could have become immediately prepared in situ as the need arises, without the need for a person to ask a processing laboratory for development and to receive prints later from the processing laboratory.
Full-color prints formed by this method, however, are disadvantageous in that images blur upon contact with water, chemicals or the like and, further, upon rubbing against hard objects, images are separated or smeared.
For example, in the electrophotographic recording method, a toner image is transferred onto an image receiving object, the toner is melted by a hot roll, and the melted toner is self-cooled to adhere and fix the toner onto the image receiving object. The records thus obtained, however, are unsatisfactory in lightfastness of images yielded by yellow toner.
Further, records produced by the ink jet recording method suffer from a problem of low lightfastness and low ozonefastness of ink jet recording inks.
To overcome the above problems, Japanese Patent Laid-Open No. 224779/1983 proposes a recording apparatus wherein a laminate material with a hot-melt adhesive is heated together with a recorded material to apply the laminate material to the recorded material.
Further, Japanese Patent Laid-Open No. 315641/1998 proposes a method wherein, in order to protect an image in a print produced by a transfer recording method such as a thermal dye sublimation transfer method or an ink jet recording method, a protective layer is thermally transferred, onto the print, using a protective layer transfer sheet comprising a substrate and a protective layer provided separably on the substrate.
The above method wherein a protective layer is thermally transferred from the protective layer transfer sheet onto an image face of a record, can provide a record with a protective layer formed thereon which has a certain level of glossy impression. The glossiness, however, is inferior to the target glossiness, that is, the glossiness of silver salt photographs, and, when the image of the record with the protective layer thermally transferred thereon is observed, the impression is that the texture and the appearance are inferior to those of silver salt photographs.
In view of the above problems of the prior art, the present invention has been made, and it is an object of the present invention to provide a thermally transferable image protective sheet and a method for protective layer formation that can provide a protective layer which can protect an image of a record produced by a nonsilver photographic color hard copy recording method, can impart lightfastness and other properties to the record, and can realize a record having a glossy impression comparable to silver salt photographs.